Loans and allowance for credit losses - Information on the risk rating of loans (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment [Line Items]
Total loans		$ 538,427
Total loans	$ 556,170
Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans		513,259
Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans		22,946
Risk Rated 6
Financing Receivable, Recorded Investment [Line Items]
Total loans		2,222
Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total loans		45,127
Total loans	50,938
Construction and land development | Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans		9,727
Total loans	7,527
Construction and land development | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans		35,400
Total loans	43,411
Construction and land development | Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans		42,490
Construction and land development | Risk Rated 1-4 | Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans		9,727
Construction and land development | Risk Rated 1-4 | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans		32,763
Construction and land development | Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans		2,637
Construction and land development | Risk Rated 5 | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans		2,637
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans		284,617
Total loans	282,921
Commercial real estate | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans		119,643
Total loans	114,964
Commercial real estate | Non-owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans		153,610
Total loans	155,139
Commercial real estate | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total loans		11,291
Total loans	12,755
Commercial real estate | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total loans		73
Total loans	63
Commercial real estate | Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans		270,647
Commercial real estate | Risk Rated 1-4 | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans		115,825
Commercial real estate | Risk Rated 1-4 | Non-owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans		143,458
Commercial real estate | Risk Rated 1-4 | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total loans		11,291
Commercial real estate | Risk Rated 1-4 | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total loans		73
Commercial real estate | Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans		12,735
Commercial real estate | Risk Rated 5 | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans		2,583
Commercial real estate | Risk Rated 5 | Non-owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans		10,152
Commercial real estate | Risk Rated 6
Financing Receivable, Recorded Investment [Line Items]
Total loans		1,235
Commercial real estate | Risk Rated 6 | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans		1,235
Consumer real estate secured by 1-4 family residential
Financing Receivable, Recorded Investment [Line Items]
Total loans		93,680
Total loans	106,532
Consumer real estate secured by 1-4 family residential | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans		18,421
Total loans	17,335
Consumer real estate secured by 1-4 family residential | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		67,495
Total loans	79,762
Consumer real estate secured by 1-4 family residential | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		7,764
Total loans	9,435
Consumer real estate secured by 1-4 family residential | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans		4,038
Total loans	4,383
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans		91,640
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4 | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans		17,507
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4 | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		66,616
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4 | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		7,517
Consumer real estate secured by 1-4 family residential | Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans		1,093
Consumer real estate secured by 1-4 family residential | Risk Rated 5 | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans		614
Consumer real estate secured by 1-4 family residential | Risk Rated 5 | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		407
Consumer real estate secured by 1-4 family residential | Risk Rated 5 | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		72
Consumer real estate secured by 1-4 family residential | Risk Rated 6
Financing Receivable, Recorded Investment [Line Items]
Total loans		947
Consumer real estate secured by 1-4 family residential | Risk Rated 6 | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans		300
Consumer real estate secured by 1-4 family residential | Risk Rated 6 | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		472
Consumer real estate secured by 1-4 family residential | Risk Rated 6 | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans		175
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans		90,348
Total loans	91,394
Commercial and industrial loans | Guaranteed student loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		20,617
Total loans	20,002
Commercial and industrial loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans		4,038
Total loans	$ 4,383
Commercial and industrial loans | Risk Rated 1-4 | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans		83,848
Commercial and industrial loans | Risk Rated 1-4 | Guaranteed student loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		20,617
Commercial and industrial loans | Risk Rated 1-4 | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans		4,017
Commercial and industrial loans | Risk Rated 5 | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans		6,481
Commercial and industrial loans | Risk Rated 6 | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans		19
Commercial and industrial loans | Risk Rated 6 | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans		$ 21